FR2591377A1 - DRIVING DEVICES FOR MAGNETIC STRIPS. - Google Patents

Abstract

This tape drive device comprises a supply reel 1 and a take-up reel 3, which are located in air-filled spaces L, H and over which the tape travels past recording-playback heads 2, a duct connecting said spaces, a retractable barrier 15 arranged between the coils, control means 17, 18 serving to close the barrier during a threading operation so that the air flow established between said spaces and passing through the guide duct the initiation of the magnetic tape from reel 1 to reel 3 inside the conduit, while the barrier can be opened by said control means during normal travel of the tape. Application in particular to video recorders. (CF DRAWING IN BOPI)

Description

The present invention relates to tape drive devices

  magnets, which use differential air pressures to achieve threading or

  automatic driving of the primer of the magnetic strip

  than from a removable supply reel, through a conduit containing the recording heads, to a

  receiver coil. Examples of such devices

  have been described, for example, in

  tannins N 987 721 and 1,141,444 and in US Patents

  N 3 393 878 and 4 243 186. In such devices, the model

  the receiver had a plurality of circumferential perforations

  or slits, formed in its perimeter wall

  and communicating with a source of pressure

  relatively low air, usually a source of

  pressure, while the periphery of the debit reel

  was located in an atmosphere with relative air pressure

  high, typically at atmospheric pressure

  or at a higher pressure. The conduit, which contains headphones

  registration and appropriate guides, leads to

  one end, in the high-pressure area and de-

  at the other end of the mouth in the

  pressure and a flow of air causes the beginning of the

  strip through the duct towards the receiving hub.

  In general, such devices function satisfactorily

  effective and reliable when handling a tape

  wearing a comparatively thick base film, that is

  that is, of a thickness of the order of 35 to 50 microns. How-

  when handling thinner tapes with

  With a base film thickness of 25 microns and less, it turned out that the first inner layers of

  the band can undergo physical deformation with an im-

  permanent pressure of the perforations of the receiving hub. In

  during use, such physical deformation may

  loss of separation between the head and the band and a lack of signal, these effects becoming apparent for high densities of linear recording of the order of 1000 bits or wavelengths per mm and more. In addition, the physical deformation can affect other layers of the wound strip during a storage period at rest on a perforated hub, and the effect can even worsen when

the storage time increases.

  Another damage to the web may be caused by the stepped portion, equal to the thickness of the web.

  band, which is formed by the beginning of the band at the

  sinage of the peripheral surface of the receiving hub. Impressions may be applied by this stepped portion to the inner layers of the wrapped web and cause a periodic disruption of the web, occurring once per rotation, which may adversely affect the recording or reading performance. at densities

high recording.

  Another drawback in such prior devices is that to obtain a satisfactory air flow in the duct, devices have been provided.

  band drive of a fixed barrier essential-

  airtight zone between the high pressure and low pressure zones, which requires that the supply reel or the

  receiving coil are widely spaced. It would be

  tagged, especially in training devices

  tapes handling large coils, possessing

  for example a diameter of 27 cm or more, such as a diameter of 36 cm, the coils are much closer to one another and allow to

  it is a more compact construction.

  Another object of the present invention is to

  to provide an improved training device for

  of magnetic, in which the mentioned disadvantages more

  high are essentially eliminated.

  This problem is solved according to the invention

  by means of a magnetic tape drive

  tick & automatic threading, with a cutting plate

  with the upper cover and side walls and supporting drive means for selectively driving a supply spool and a take-up spool, the supply spool being disposed in a first air-filled space which, during an operation of threading, is in

  communication with a source of relative air pressure-

  high, and the receiver coil being positioned in a second air-filled space which during an operation

  threading, is in communication with a source of pres-

  relatively low airflow, a duct connecting the first

  first and second spaces filled with air, and a barrier

  tractable disposed between the supply spool and the take-up spool, control means being provided for closing the barrier during a threading operation so that

  the flow of air established between the first and second spaces

  these filled with air and circulating in the duct can guide the primer of the magnetic tape from the supply reel through the duct, towards the receiver coil,

  said control means being operable in such a manner that

  re to open the barrier during normal movement of the tape.

  Other features and advantages of the pre-

  invention will emerge from the description given below.

  after making reference to the accompanying drawings, in which:

  FIG. 1 is a plan view of a device

  tif tape drive during an opera-

  threading; FIG. 2 is a plan view of the drive device during the normal running of the strip; FIG. 3 is a side elevational view of a cover and a cover plate, showing a

shutter in the rotated position; -

  Fig. 4 is a perspective view of a second embodiment of a cover plate, showing a flexible barrier;

  FIG. 5 illustrates the actuation of the bar

  flexible; FIG. 6 is a perspective view of a receiver coil;

  FIG. 7 is a plan view of the flange

  bottom of the receiver coil; - Figure 8 is a side elevational view in diametral section of a receiver coil; Figure 9 is a side elevational view in diametral section of a second embodiment of a take-up spool; and FIG. 10 is a plan view of a hub for use with the second embodiment

a receiver coil.

  A plan view of a training device

  of a strip, suitable for making a recording

  very high density, is shown in Figure 1, on

  which the tape delivered by a reel removable reel

  ble 1 equipped with a wide flange, is trained in front of

  recording and reading 2, to be wound on

  a receiver coil 3 having small flanges.

  The use of small flanges on the coil

  receiver allows a compact arrangement, in which the ban-

  coiled on the receiver coil can be

  compared to small flanges and, when the coil

  the debtor is emptied of the tape, the unsubstantiated tape block

  held and protruding from the receiver coil can freely

  extend between the flanges of the supply spool as shown in FIG. 2. A follower 4 of the strip block, which is attached to a pivoting arm 5 around the spool.

  point S. is in a retracted position during

  spinning, as shown in Figure 1, and,

  normal scrolling, is repulsed by

  in the form of a spring towards the periphery of the band

2 5 9 13 7 7

  rolled to guide the protruding web block

  A follower roller of the tape block has small flasks

  guiding the band, and at the same time the wheel 4 and the

  arms 5 are typically made of an aluminum alloy

  light nium. The path of movement of the strip has two

  rotary devices 7 for tensioning, constituted each

  by a pair of rotary guide fingers 8, three

  guide lugs 9 and a pair of capstans 10 driven from

  differential way. An optional provision may be

  tif tape cleaning, which is made up of a couple

  of cartridges 11 each containing a cloth cleaning the ban-

  of this fabric being retractable so as to establish a

  clear motion jet for threading the tape.

  Engines (not shown) are mounted

  under a cover plate 6 so as to drive the supply spool and the take-up spool and the capstans, and the servo-control device of the setting devices

  voltage, and there is provided actuating means for

  both of suitably retracting the web block follower roller and web cleaning fabric to allow threading thereof. The motors and the actuating means are controlled by a microprocessor,

  so as to allow automatic operation.

  The belt drive device is equipped with means for automatically threading the free end of the web from the supply reel, along the path of travel of the web and onto the take-up reel of a web. way that does not require any

  perforation of the surface of the receiver coil, which

  tacte the band. The underside of the take-up reel

  is subject to the action of a relative pressure source-

  lowermost, and the periphery of the debiting reel

  only in zone 'A', through perforations in the cover plate, with a relatively high source of air pressure, there is provided an upper cover 14 for transport. on the cover plate constitute walls on both sides of the travel path of the web

  and extending to the top cover so as to form

  a duct which is essentially airtight, and the strip can be automatically threaded on the guide rollers, the heads, the capstans, the tensioning devices and, when they are put in place, between the cartridges of cleaning the strip, by drawing air through the duct. Sources of low pressure and high pressure can be suitably formed respectively

  by the admission and exit of a fan (not shown -

  It is mounted below the cover plate and, when in operation, places the area H in the vicinity of the supply reel at a high pressure and the area L located in the vicinity of the reel at a low pressure. Referring also to Figure 3, we see

  that a rigid shutter 15 is mounted so as to be able to

  voting from one side or the other of its upper edge at points P and R, with respect to the wall elements 13 and 19 forming respectively part of the covering plate,

  so that when in the vertical position

  (Figure 1), the shutter establishes a barrier

  air-tight between zones H and L, while being positioned in such a way that a large coil of belt 1, typically 27 cm in diameter, can penetrate completely into zone H and placed on the debtor hub 16. An articulated opening member 40

  is provided on the end of the cover 14 so as to allow

  Be loading a supply reel on the hub, without removing the cover. The shutter 15 can also be pivotally brought into a horizontal position (FIG. 2).

  o it is located above the surface level above

  of the supply reel 1, and means are provided for

  17 in the form of an actuator or motor, provided with a transmission

  gearing 18, to actuate the shutter automatically.

  The shutter is arranged vertically, that is

  that is, it is closed during the threading of the band, as illustrated in FIG. 1, and is arranged horizontally,

  that is, it is open during normal scrolling

  wrong, case illustrated in Figure 2. It is seen that during normal scrolling ,. there is no barrier between the

  debiting coil. and the receiver coil, and the coils can

  They can be placed in positions relatively close to each other since the tape wound on the take-up reel can enter the space between the flanges of the supply reel. In the devices

  automatic threading belt drive of the art

  it was necessary that the center-to-center distance

  be coils greater than the diameter of the coil de-

  to provide space for a fixed barrier

  the high and low pressure zones, while the present invention, which uses a retractable barrier,

  allows a center-to-center distance well below the

meter of the debtor coil.

  Another form of retractable barrier is

  shown in Figures 4 and 5. Areas H and L at high

  pressure and at low pressure, which are

  For the supply reel and the take-up reel, there are provided storing recesses 19 and 20 in a cover plate 21, and a conduit 22 connecting the depressions.

  is intended for the heads, the guides, the. half-way devices

  tension and the capstans. A retractable barrier is formed by a flexible plastic strip 23, which is

  wound on a capstan 24 loaded by a spring. The extré-

  of the plastic strip can be drawn on a track whose shape corresponds to a part of a circle,

  to form a barrier between the coils, at least

  yen of a wire 25 connected to a motor 26. Domestic grooves

  in the upper surface of the cladding plate and in the lower surface of the hood define the track, and the wire may be connected either to the upper part or

  & the lower part of the end of the strip in terms of

  plastic in order to circulate in one or other of the

  grooves. Turning on the motor 26 causes the

  the wrapped plastic strip and forms

  a barrier for threading the tape, while half

  when the engine is stopped, the tape can be rewound

  and the barrier is removed for scrolling

the tape.

  A receiver coil 3 having no

  drilling on the outer surface of its hub 27 is

  shown in Figures 6 and 8. A lower flange 28

  is provided with a plurality of recesses 31 formed in

  It has radial slots, which leads to a number of elongated through holes 29 located on a circle whose outer diameter is smaller than the diameter of the web contacting member. A number of screw holes 30 are provided in the span extending between the holes 29 of

  in order to allow the fixing of the flange 28 to the hub 27.

  A small upper flange 37 provides additional guidance.

  the band, although this flange is not essential.

  tiel in the case of tape drives installed horizontally. During a threading operation of the strip, a delivery reel is manually loaded.

  through the articulated opening member 40, the entry being

  airtight when closed. The other operations are then fully automatic, the

  appropriate motors and actuators are controlled by a

  programmed croprocessor. During a threading operation,

  the fan is connected, the follower roller of the bank block

  is retracted and the pivoted shutter 15 or the flexible barrier

  xible 23 is closed. The fan causes a flow of air from the high pressure zone H to the zone

  low pressure L and the air is drawn through the

  31 and the holes 29 and enters the zone Q, below the coating plate, which communicates

  with the admission of the fan, the direction of the

  air being represented by the arrows XX. The cover plate has a circular orifice having a counterboring 32 of low height. The shaft 33 of the rewinding motor, to which an inner hub 41 is attached, is mounted concentrically to the orifice, and the counter-boring is dimensioned so as to provide a fair play sufficient to

  free rotation, but negligible air leakage. The modalities

  unwinding and rewinding machines are then set in slow rotation and are synchronized so that the

  linear speed of the periphery of the receiving hub is es-

  sensitively equal to the linear velocity of the band during

  that the latter begins to leave the hub of the supply reel. The airflow initiates the T-band through the duct and introduces it into the vicinity of the hub

  receiver, as shown in Figure 1, the lower edge

  the tape being pulled into soft contact with the door

  between the radial recesses 31 of the inner flange

  bottom and being made to loosely wrap around the face of the hub. After three or four rotations, the tensioning devices of the web are brought into operation and the speeds of the motors are appropriately controlled so that the web can be

  stretched and tighten firmly on the hub.

  When tripping the normal operation of the strip, the relevant motors and actuators are energized, the fan is disconnected and the shutter

  rotated or the flexible barrier is open. When the

  of the block formed by the band wound on the bobbin

  ceptrice extends beyond the flanges 28, 37, the roller follower 34 of the block of the strip is activated so as to provide

  a guide, as shown in Figure 2.

  It has been found that in operation of a tape drive as described above in an analogous mode using signals having a very short wavelength, typically in the order of one micron, there was no trace of any

  of the band or an associated alteration of the

  because of contact with the face of the hub, as it is

  the case with the perforated hubs of the prior art. How-

  during operation with such lengths of on-

  short, it turned out that when the surface of

  tact of the hub is formed by a metal, for example aluminum

  minium or an aluminum alloy, it may appear

  periodic mechanical disturbances, intervening at the frequency

  this of once per rotation, because of the tiered part

  formed by the beginning of the band located in the vicinity of the sur-

  peripheral face of the receiving hub, and this effect can

  shot at a sinking of a significant number of layers of

  the band, which adversely affects the response of the

  gnal. This effect proved to be particularly noticeable

  when using a follower roller of the belt block,

  with a metal contact surface.

  It turned out that one can eliminate in a

  This form of signal alteration is largely

  screwing the face of the hub by a thin elastic layer 33, preferably constituted by an elastomeric material based on

  polyurethane, such as the product referred to

  CIL-MONOTHANE trade mark (trade mark), which is

  can be obtained from the so-called Compounding In-

  Limited gredients. There was an additional improvement

  when applying a similar elastomer coating

  ble on the contact surface of the follower roller of the belt block. A thickness suitable for such coatings in

  elastomer is of the order of 0.25-1.5 mm and is equal in

  typically 0.5 mm. The use of an unperforated receiver coil has a second advantage that the non-perforated surface can be easily covered by an elastomer. If we covered a perforated spool

  elastomeric material, it is likely that the

  would be entirely or partially covered by the elastomer, whereas if the perforations were formed after overlapping the surface of the

  tend to become clogged as a result of the elasticity of the

  is lying. A second embodiment of the coil

  receiver is shown in Figures 9 and 10, on the

  which the lower flange 28 is not modified, but the

  hub 34 has a plurality of through holes allon-

  located between fixing holes 36, these holes being

  aligned with the holes 29 and 30 formed in the inner flange

  28. The lower surface of the upper flange 28 is provided with an annular recessed area 39, which is

  out of the outer peripheral surface

  hub and thus allows the following air flow

  the direction of the YY arrows when the fan

  operates, driving the upper part of the

  of the web towards the upper part of the hub surface, in addition to the airflow XX which acts

  to a large extent on the lower part of the

the band.

  The invention has been described by way of example and many other embodiments of the invention.

  will be apparent to those skilled in the art.

Claims (14)

  1. Magnetic tape drive   automatic threading, characterized in that it comprises   a cover plate (6; 21) provided with a top cover   (14) and sidewalls and supporting means   of training for coachingelectivelyrotating a booster   a debtor (1) and a take-up spool (3), among   the supply reel (1) is disposed in a first   first space filled with air (H) which, during the operation of   spinning, is in communication with a relatively high source of air pressure, and the receiver coil (3) is   placed in a second space filled with air (L) which,   during the threading operation, is in communication with a relatively low air pressure source, a conduit (22) connecting the first and second air-filled spaces, and a   retractable barrier (15) disposed between the debit coil   this (1) and the receiver coil (3), and that there are   control means (17, 18) for closing the bar   during a threading operation so that   the flow of air established between the first and second spaces   these filled with air through the conduit allows for   guide the start of the magnetic stripe from the reel   bit (1) in the conduit to the receiver coil (3), said control means being operable from   to open the barrier (15) during the normal scrolling bad of the band.   Tape drive according to claim 1, characterized in that the receiving spool (3) is provided with a single flange (28) on one side of the spool or a pair of flanges ( 28,37) located   two sides of the coil and which have a diameter   be relatively small so that a block of tape   coil may be protruding from the (x) flange   that (s), the supply reel (1) having a pair of flasks   relatively large, extending radially outwardly beyond a fully wound band block, and the center-center distance between the supply reel (1) and the receiving reel (3) being less than the diameter of the   the debiting reel so aue, Dending the normal scrolling   of the web, a protruding web block of the reel may extend through the open barrier (15) to extend freely between the webs of the web. debiting coil.   Belt drive device according to claim 2, characterized in that it comprises a retractable roller (4), which follows the wound tape block and which is pushed back slightly in the direction of this tape block.   salient, during the normal scrolling of the band.   4. Belt drive device according to claim 3, characterized in that at least the surface of said roller (4), which contacts the strip, is made of a elastic material.   5. Tape drive according to the   claim 4, characterized in that said elastic material   tick is a polyurethane elastomer in the form of a layer having a thickness of 0.25 and 1.5 mm.   6. Belt drive device according to one   Claims 1 to 5, characterized in that the barrier   retractable is constituted by a pivoting flap (15).   7. Tape drive according to   any of claims 1 to 5, characterized in that   the retractable barrier (23) is constituted by a   flexible strip (1) that can be pulled across the   between the receiver coil and the coil   trice. Tape drive according to claim 7, characterized in that grooves are provided in the facing surfaces of the cover plate (21) and the cap (14) so as to forming peaks for the edges of the flexible band (23). 9. Tape drive according to   one of the claims 7 or 8, characterized in that   it is retracted, the flexible band (23) is wound   on a capstan (24) loaded by a spring and that it is pre-   saw a motor (26) and a wire (25) connecting the motor to the amor-   this of the flexible band so that when the   is switched on, the flexible band is drawn in   towards the space between the receiver coil and the coil of bitrice.   10. Magnetic tape drive   automatic threading, characterized in that it comprises   a cover plate (6; 21) provided with a top cover   (14) and side walls and which supports   yen training to train in the choice of   a supply reel (1) and a take-up reel (3), among which the supply reel (1) is arranged in a first air-filled space (H) which, during the operation   threading, is in communication with a source of pres-   relatively high air pressure, and the receiving coil (3) is positioned in a second air-filled space (L) which, during the threading operation, is in communication with a source of relatively low air pressure, a conduit (22) connecting the first and second air filled spaces of   such that, during a threading operation, a hearing aid   of air established between the first and second spaces   folds of air passing through the duct realized guiding   the beginning of the magnetic tape from the debit coil   (1) by taking the conduit (22) to the reel   ceptrice (3), that the receiver coil (3) has a modulus   yeu (27) having a non-perforated web support surface and a lateral flange (28) extending radially to   the outside of the hub and located in close proximity to the   coating (6j21), that the source of relatively low air pressure can be connected to a hole   in the cladding plate below the reel   the surface opposite the web of the side flange (28) is provided with a plurality of slots (31) extending substantially radially inwardly.   the support surface of the hub strip and   to a number of orifices (29) households in the over-   face of the coil facing the liner plate, allowing the air flow established through the slots   radials to lead the beginning of the band by bringing   direct proximity to the unperforated support surface of the belt. 11. Tape drive according to   claim 10, characterized in that the coil receiving   trice (3) is provided with a second lateral flange (37) extending   radially outwardly from the hub (27).   12. Tape drive according to the   claim 11, characterized in that the surface,   next to the band, the second flange (37) is   denoted by a plurality of radially extending slots   inwards from the support surface of the   band, which the hub has, and resulting in a plurality of   of essentially axial passages in the modulus   yeu and which communicate with said orifices located in to the facing plate.   13. Tape drive according to   any of claims 10 to 12, characterized in that   what said support surface of the strip is covered   by a layer of an elastic material.   Belt drive device according to claim 13, characterized in that said layer in   an elastic material is constituted by an elastomer   of polyurethane having a thickness of between 0.25 and 1.5 mm.